This proposal addresses the definition of cellular mechanisms involved in the transcriptional activation of the HIV-1 provirus. Our previous studies have resulted in the identification of a complex set of cellular proteins that interact with control elements within the HIV-1 long terminal repeat (LTR). We have identified inducible and cell type specific proteins that interact with the duplicated kappaB site in the LTR. We have also established a microscale in vitro transcription assay to study the biochemical properties of extracts from cells at different growth stages to assess the transcriptional activity of the HIV-1 LTR and how different control elements within the LTR contribute to that activity. We are now in a position to use what we have learned and the systems that we have operational to determine if certain of the proteins interacting with the kappaB sites in the HIV-1 LTR are necessary for transcriptional activation of resident, integrated provirus. We will focus on a thorough characterization of one of the kappaB binding proteins, Rel (HIVEN86A) because we have demonstrated it to be inducible and because both the CDNA and various immunologic reagents are now available to permit structure and function analysis of the protein. We will use the anti-sense oligonucleotide approach to disrupt the production of Rel and determine the effects in cells that have the HIV-1 provirus stably integrated. We will also study the effects of over expression of Rel or disruption of expression of Rel in cells acutely infected with HIV-1. We will continue to characterize and to develop reagents for the study of the other kappaB binding proteins especially the proteins we have demonstrated to be cell type specific.